What is Amazon CloudWatch Logs?

You can use Amazon CloudWatch Logs to monitor, store, and access your log files from
Amazon Elastic Compute Cloud (Amazon EC2)
instances, AWS CloudTrail, Route 53, and other sources. You can then retrieve the
associated log data from
CloudWatch Logs.

Features

Monitor Logs from Amazon EC2 Instances—You can use CloudWatch Logs to monitor applications and systems
using log data. For example, CloudWatch Logs can track the number of errors that
occur in your
application logs and send you a notification whenever the rate of errors exceeds
a
threshold you specify. CloudWatch Logs uses your log data for monitoring; so,
no code changes
are required. For example, you can monitor application logs for specific literal
terms (such as "NullReferenceException") or count the number of occurrences of
a
literal term at a particular position in log data (such as "404" status codes
in an
Apache access log). When the term you are searching for is found, CloudWatch Logs
reports the
data to a CloudWatch metric that you specify. Log data is encrypted while in transit
and
while it is at rest. To get started, see Getting Started with CloudWatch Logs.

Monitor AWS CloudTrail Logged Events—You can
create alarms in CloudWatch and receive notifications of particular API activity
as
captured by CloudTrail and use the notification to perform troubleshooting.
To get started, see Sending
CloudTrail Events to CloudWatch Logs in the AWS CloudTrail User Guide.

Log Retention—By default, logs are kept indefinitely
and never expire. You can adjust the retention policy for each log group, keeping
the
indefinite retention, or choosing a
retention periods between 10 years and one day.

Archive Log Data—You can use CloudWatch Logs to
store your log data in highly durable storage. The CloudWatch Logs agent makes
it easy to quickly send both rotated and non-rotated log data
off of a host and into the log service. You can then access the raw log data when
you need it.

Log Route 53 DNS Queries—You can use CloudWatch Logs to
log information about the DNS queries that Route 53 receives. For more information,
see
Logging DNS Queries in the Amazon Route 53 Developer Guide.

Related AWS Services

The following services are used in conjunction with CloudWatch Logs:

AWS CloudTrail is a web service that enables you to monitor the
calls made to the CloudWatch Logs API for your account, including calls made
by the AWS
Management Console, command line interface (CLI), and other services. When CloudTrail
logging is turned on, CloudTrail captures API calls in your account and delivers
the log
files to the Amazon S3 bucket that you specify. Each log file can contain one
or more
records, depending on how many actions must be performed to satisfy a request.
For more information about AWS CloudTrail, see What is AWS CloudTrail? in the
AWS CloudTrail User Guide. For an example of the type of data
that CloudWatch writes into CloudTrail log files, see Logging Amazon CloudWatch Logs API Calls in AWS CloudTrail.

AWS Identity and Access Management (IAM) is a web service that helps you
securely control access to AWS resources for your users. Use IAM to control
who can use your AWS resources (authentication) and what resources they can use
in which ways (authorization). For more information, see What is IAM? in the
IAM User Guide.

Amazon Kinesis Data Streams is a web service you can use for rapid and
continuous data intake and aggregation. The type of data used includes IT
infrastructure log data, application logs, social media, market data feeds, and
web clickstream data. Because the response time for the data intake and
processing is in real time, processing is typically lightweight. For more
information, see What is
Amazon Kinesis Data Streams? in the Amazon Kinesis Data Streams Developer Guide.

AWS Lambda is a web service you can use to build
applications that respond quickly to new information. Upload your application
code as Lambda functions and Lambda runs your code on high-availability compute
infrastructure and performs all the administration of the compute resources,
including server and operating system maintenance, capacity provisioning and
automatic scaling, code and security patch deployment, and code monitoring and
logging. All you need to do is supply your code in one of the languages that
Lambda supports. For more information, see What is AWS Lambda? in the
AWS Lambda Developer Guide.

Pricing

When you sign up for AWS, you can get started with CloudWatch Logs for free using
the AWS Free Tier.